A new iteration of the dude-bro Dionysian comedy, Last Vegas is a reverse Mentos commercial in which the clever old people have to outwit the entitled, selfish young people in order to get into the nightclub or yank a casino's penthouse suite away from a formerly respectable hip-hop artist now slumming in lazy, mid-budget comedies. Presumably, the cast's enthusiasm to work together was greater than their enthusiasm for the script, a sitcom-level tissue of broad jokes, flat gags, and lazy coincidences. But what the film has in spades is charm, its four co-stars leveraging obvious mutual admiration and roughly 160 man-years of comic experience for some genuine onscreen chemistry. When 70-year-old bachelor Billy (Michael Douglas) proposes to his much younger girlfriend -- at a funeral, while delivering the eulogy -- his three childhood friends insist on throwing him the same Las Vegas bachelor party he'd thrown in their honor decades before. Sam (Kevin Kline), who hasn't boned his wife in a decade, gets tacit permission to cheat during the long weekend. Paddy (Robert De Niro) is in extended mourning for his deceased wife. And Archie (Morgan Freeman, who is the greatest), a twice-divorced stroke survivor in fear of recurrence, has consigned himself to a hermetic life in his overprotective son's home. The film's hidden asset is the luminous Mary Steenburgen, funny and gorgeous as an empty-nest mom turned lounge chanteuse who beguiles the dudes with age-appropriate flirting and arch humor. The characters are totally passive -- money, drinks, women, and unexpected acclaim shower down on the elder-bros like Werther's Originals from God's own cardigan pocket, completely unearned by the characters or the screenplay.